Two administration officials confirmed Trump's plans. A Republican congressional aide said the president was expected to announce his decision by tweet on Friday morning. The officials were not authorized to speak publicly before Trump's announcement.

FILE - In this Aug. 9, 2017, file photo, State Department spokeswoman Heather Nauert speaks during a briefing at the State Department in Washington. President Donald Trump is expected to nominate Nauert to be the next U.S. ambassador to the United Nations. (AP Photo/Alex Brandon, File)

Ambassador to the U.N. Nikki Haley will step down at the end of the year. She made the official announcement during an October news conference held in the oval office with President Trump.

"I have given everything I've got these last eight years," she said, referring to her six years as South Carolina governor as well as her time at the U.N. "And I do think it's good to rotate in other people who can put that same energy and power into it."

Trump has been known to change course on staffing decisions in the past.

Nauert was a reporter for Fox News Channel before she became State Department spokeswoman under former secretary Rex Tillerson.